The present disclosure relates to the field of oncology and more particularly to the radiolabeling of a cancer detection agent.
Sentinel node biopsy is rapidly gaining acceptance as a common practice for melanoma and breast cancer diagnosis (Vera, D. R. et al. (2001) J. Nucl. Med. 42, 951-959). This technique has not been standardized; it typically involves the use of a 99mTc-colloid and a blue dye. The radioisotope, 99mTechnetium, that is used in the colloid imaging agent and in the current invention, has several desirable properties: its ready availability, relatively low cost, excellent imaging quality, and its short half-life of 6 hours. This radiotracer is employed preoperatively to ascertain the location of the sentinel node and, then, it is used intraoperatively to pinpoint the dissection of the sentinel node(s). The blue dye, which is cleared rapidly through the lymph channels and nodes, is used to visually confirm the selection of the radioactive node as the sentinel node. Because this biopsy procedure varies with individual practitioners, it is difficult to train practitioners with a consistent skill set and consequently, these biopsies result in a wide range of reported false-negative rates (i.e., 0 to 12%—see Vera, D. R. ibid.).
There is another hurdle to standardization of this sentinel node biopsy technique. There is no blue dye or 99mTc-labeled agents specifically designed for sentinel node detection or extraction. Currently, the FDA (U.S. Food and Drug Administration) has not approved any dye, or 99mTc-labeled agent for sentinel node diagnosis. Thus, the following radiopharmaceutical agents are used off-label: 99mTc-sulfur colloid, filtered 99mTc-sulfur colloid, 99mTc-antimony trisulfide, and several preparations of 99mTc-labeled albumin microcolloids. (Note: Colloids are non-targeted particles that are sticky.) None of these agents display ideal properties of rapid injection site clearance or high sentinel node extraction (Hoh, C. K., et al. (2003). Nucl. Med. Biol. 30, 457-464).
Hence, the development of a nuclear imaging diagnostic kit that is designed to meet the goals of optimal sentinel node detection (i.e., rapid injection site clearance and low distal lymph node accumulation) is an unmet medical need in breast and melanoma cancer treatment.